Process for conversion of alkyldecalins and/or alkyltetralins

ABSTRACT

A process for conversion of a feed consisting essentially of an alkyldecalin or an alkyltetralin (or a non-equilibrium mixture thereof) comprises contacting the feed with an alumino-silicate zeolite containing polyvalent metal cations in exchange positions, the contacting being at a temperature in the range of 100-350*C., liquid hourly space velocity in the range of 0.25 to 10 and a pressure in the range of 15 to 1500 psig.

United States Patent Hedge et al.

PROCESS FOR CONVERSION OF ALKYLDECALINS AND/0R ALKYLTETRALINS Inventors: John A. Hedge, Wilmington, Del.;

George Suld, Springfield; Ralph L. Urban, Newtown Square, both of Assignee: Sun Ventures, Inc., St. Davids, Pa.

Filed: Apr. 8, 1974 App]. No.: 458,962

US. Cl. 260/668 F; 260/668 A, 260/672 T Int. CI. C07C 5/24; C07C 15/20 Field of Search 260/668 A, 668 F, 672 T References Cited UNITED STATES PATENTS 4/1974 Suld et a1 260/668 A Dec. 23, 1975 Primary Examiner-C. Davis Attorney, Agent, or Firm-George L. Church; Donald R. Johnson; J. Edward Hess ABS I'RACT pslg. v I

l2 Claims, 14 Drawing Figures US. Patent De 23, 1975 Sheet10f14 3,928,482

HIGH TEMPERATURE (200C) EQUILIBRIUM ISOMERIZATE 'OF C-IZ DICYCLICS (RU-5008 A+ B) US. Patent Dec.23, 1975 Sheet20f 14 3,928,482

Fig. 2

LOW TEMPERATURE (AMBIENT) EQUILIBRIUM ISOMERIZATE OF C-l2 DICYCLICS (RU-5020-2) US. Patent Dec. 23, 1975 Sheet3of 14 3,928,482

Fig. 3

(PART I) I50" UCON CAP. COLUMN U.S. Patent Dec. 23, 1975 Sheet4of 14 3,928,482

US. Patent Dec.23, 1975 SheetSof 14 3,928,482

Fig. 4

CATALYSATE FROM DEHYDROGENATION OF THE "NON-DEHYDROGENATABLE" FRACTION A' FROM THE DMD HIGH TEMPERATURE EQUILIBRIUM ISOMERIZATE (RU5024-2) NON-DEHYDROGENATABLES US. Patent De :.23, 1975 Sheet6of 14 3,928,482

Fig. 5

HIGH TEMPERATURE DMD EQUILIBRIUM ISOMERIZATE RE-ISOMERIZED AT ROOM TEMPERATURE (RUSOZO-I) US. Patent Dec. 23, 1975 Sheet7of 14 3,928,482

Fig. 6

2,6-DMN US. Patent Dec.23, 1975 SheetSof 14 3,928,482

Fig. 7

TYPICAL LOW TEMPERATURE DMD EQUILIBRIUM ISOMERIZATE, DEHYDROGENATED (RU502O-2-H 2,6-DMN 2-MeN US. Patent Dec. 23, 1975 Sheet9of 14 3,928,482

Fig. 8

. ISOMERIZATE FROM 2,7-DMD's OVER SK-I30, 200C US. Patent Dec. 23, 1975 shw 10 of 14 I 3,928,482

Fig. 9

ISOMERIZATE FROM 2,3-DMD'S OVER SK-|3)'O, 200 C U.S. Patent Dec.23, 1975 Sheet11of14 3,928,482

Fig. 9

(PART 2) US. Patent Dec. 23, 1975 Sheet 12 of 14 3,928,482

U.S. Patnt Dec.'23, 1975 Sheet 13 of 14 3,928,482

AM NK ZOO DEV P920 aux-2 m0 m 0 omm 0200mm U.S. Patant Dec.23, 1975 Sheet 14 of 14 3,928,482

3E5 mEE. 1 O m PROCESS FOR CONVERSION OF ALKYLDECALINS AND/OR ALKYLTETRALINS CROSS REFERENCES TO RELATED APPLICATIONS U.S. applications Ser. No. 263,372 filed July 6, 1972 and Ser. No. 7,273 filed Jan. 30, 1970 of John A. Hedge (now US. Pat. No. 3,668,267 issued June 6, 1972) disclose methods for separation of 2,6-DMN from 2,7-DMN by adsorption on certain molecular sieve zeolites, which zeolites can be used as catalysts in the present process. United States application Ser. No. 99,280 of George Suld and Ralph L. Urban filed Dec. 17, 1970 (now US. Pat. No. 3,721,717 issued Mar. 20, 1973 describes a pulse microreactor which can be used for experimental work'relative to the present invention. U.S. applications Ser. No. 21 1,040 filed Dec. 22, 1971 (now US. Pat. No. 3,839,228 issued Oct. 1, 1974) and Ser. No. 716,190 filed Mar. 26, 1968 (now US. Pat. No. 3,865,894 issued Feb. 11, 1975) of Kirsch, Barmby and Potts diclose methods for activation of zeolite catalysts (especially rare earth exchanged, protonated, zeolite Y) to control water content. Applications Ser. No. 207,870 (now US. Pat. No. 3,855,328 issued Dec. 17, 1974) of JohnA. Hedge and ser. No. 208,001 (now US. Pat. No. 3,803,253 issued Apr. 9, 1974) of George Suld and Ralph L. Urban both filed Dec. 14, 1971 describe certain catalysts and processes for isomerization, disproportionation and hydroisomerization of dimethylnaphthalenes and dimethyldecalins.

The entire disclosure of all of the above-cited patents and copending applications is hereby incorporated herein by this reference.

BACKGROUND OF THE INVENTION SUMMARY OF THE INVENTION Alumino-silicate zeolites (preferably zeolites containing polyvalent metal cations) can be used to catalyze alkyl transfer, e.g., isomerization, transalkylation and disproportionation of alkyldecalins' in the presence of to 1,000 psi of hydrogen. The water and metal cation content of the zeolite and the reaction conditions (particularly temperature and space velocity) can be selected so as to favor one such reaction over the others and to eliminate undesired side reactions (e.g., cracking). The preferred zeolites are at least crystalline by X-ray, can adsorb benzene, and have an atomic ratio Al/Si in the range of 1.0 to 0.1. The preferred zeolites have the faujasite framework structure (e.g., Linde Type Y) and contain nickel and/or rare earth cations (e.g., cerium and/or lanthanum, etc.)'in exchange positions. The zeolite can also contain or be used in admixture with a noble metal hydrogenation catalyst (e.g., platinum, palladium, ruthenium, rhenium and mixtures thereof).

. 2 The zeolite catalysts and process steps described in US. Pat. No. 3,668,267, US. Pat. No. 3,803,253, Ser. No. 207,8 70 and Ser. No. 208,001 can also be used for isomerization of dimethyldecalins. One objective is to 5 isomerize a dimethyldecalin mixture to increase the amount of trans, syn-2-syn-6-dimethyldecalin (TSS- 2,6-DMD). This isomer can be removedby low temperature crystallization (e.g., see US. Pat. No. 3,541,175 to Hedge issued Nov. 17, 1970) and the remaining dimethyldecalins can then be re-equilibrated.

The preferred temperature is in the range of C to 350C, more preferred C to 250C, typically about C to 200C.

FURTHER DESCRIPTION Isomeriz'ation rates of dimethyldecalins with RE-Y (i.e., rare earth exchanged Type Y zeolite) sieves at C were slower than for dimethylnaphthalenes. Furthermore, the desired TSS-2,6-DMD isomer was found to be present in significantly lower amounts at 190C. Only about 13% TSS-2,6-DMD constituting ca. 60% of the total 2,6-DMD isomers, is present at equilibrium at 230C versus about 25% TSS-2,6-DMN at 29C.

For example, 2,7-dimethyldecalin (2,7-DMD) can be isomerized at 190C by rare earth exchanged Type Y molecular sieve (e.g., Linde SK-500). The isomerized DMD mixture upon dehydrogenation over palladium on carbon contains:

7.0% 1 8L 2 Ethylnaphthalene 21.5% 2.6-DMN 21.5% 2,7-DMN 43.0% Other DMNs 7.0% 2,3-DMN Note that this conversion is not possible with dimethylnaphthalenes since the 2,6-DMN and 2,7-DMN families are not interconvertible. The isomerizate is water white; thus sieve life between recycles may be considerably longer than for the 1,6-DMN to 2,6-DMN isomerization described in US. Pat. No. 2,803,253. Hydrogen pressure (e.g., 15 to 15,000 psi) can also be used to prolong catalyst life.

A single isomer was used in the run described above in order to facilitate analysis. However, the process can involve isomerization of the entire mixed DMD stream obtained byhydrogenation of a 495F to 518F heart cut from an extract of catalytic gas oil.

Other acidic zeolites can also isomerize DMDs. Decationized zeolites and metal exchanged zeolites are examples of such acidic zeolites. Water content of these sieves may be critical for desired activity, as determined by screening runs.

A wide range of temperatures are applicable. The hydrocarbon can be in liquid or vapor or mixed (e.g., trickle) phase. Rate of catalyst deactivation versus desird conversion rate will govern the optimum operating temperature and reaction time.

The above disclosed decalin isomerization (or hydroisomerization) can be conducted in the presence of alkyltetralins.

Tetralins can also be converted using the catalysts and Conditions described herein. Isemerlzatlen, or'hy droisomerizatien of the methyl group on the aromatic ring of three dimethyltetralin isomers yields 2,6='dimethyltetral in (2,6-DMT). This reaction is further de= 3 scribed in Ser. No. 208,001. Acidic zeolites at 150C to 300C (e.g., 190C to 250C) can catalyze this isomerization. If hydrogen (e.g., to 1,000 psi) is used, a noble metal hydrogenation catalyst can also be present to improve catalyst life and/or yields.

Approximately to 33% 2,6-DMT is present in the equilibrium mixture at 28C starting with pure, 2,7- DMT or 1,7-DMT. With mixed DMTs from a dimethylnaphthalene concentrate, other DMT isomers which are not convertible to 2,6-DMT are present, and the amount of 2,6-DMT in the isomerizate is only 25% greater than in the charge (from 13.6% in the charge up to 17.3% 2,6-DMT in the isomerizate).

ILLUSTRATIVE EXAMPLES An isomerization study was made wherein the model compounds used were the mixtures of configuromers of 2,3- and 2,7-DMDs derived from the exhaustive hydrogenation of the corresponding DMN isomer. In both instances four vapor phase chromatography (VPC) peaks were observed under the standard VPC analysis conditions. In addition to the two position isomers a mixed DMD concentrate was employed in the major part of the investigation. As in the case of DMNs in Ser. No. 208,001, screening studies were carried out in a pulse microreactor. Due to the complexity of both the starting material and the isomerized DMD product only a gross measure of the over-all isomerization reaction could be obtained by the combined pulse-microreactor-VPC technique. However, comparison of the VPC trace of the DMD isomerizate with the starting material and a corresponding scan of the known DMD equilib rium isomerizate gave a good measure of the extent of the reaction and hence the relative activities of each catalyst screened.

To determine the quantitative distribution between the groups of position isomers the samples of the catalysates were collected as they emerged from the gas chromatography column and dehydrogenated in a microreactor over Houdry 3-J halide free. catalyst.

Table I summarizes the results obtained with a mixed DMD charge in a pulse microreactor. The catalysates contained, in addition to the compounds boiling in the DMD range, varying amounts of lighter hydrocarbons. The latter consisted of a mixture of paraffins, cycloparaffins and olefins. This hydrocracking and/or cracking reaction was again due to the severity of the conditions, i.e., the minimal temperature limitation imposed by the pulse microreactor VPC analyzer technique requiring a vapor phase operation.

On the basis of the pulse microreactor study, the catalysts employed could be divided, according to their activity, into two groups:

1. Catalysts with no isomerization activity at standard conditions and cracking-hydrocracking activity at higher temperatures, e.g., SK-200, H-Zeolon.

2. Catalysts with isomerization activity such as rare earth exchanged mole sieves, e.g., SK-l30, Ce- NH +/Y, La-NH +/Y, nickel and palladium exchanged sieves, e.g., Ni-NH +/Y, SK-lOO.

In the screening study one phenomenon was observed that had not been encountered in the isomerization of DMDs at low temperatures with Lewis acidcocatalyst systems (e.g., AlCl HCl or HFBF Thus, although the gross features of the VPC trace of the 200C, mole sieve catalyzed DMD equilibrium isomerizate resembled low temperature (29C) Lewis acid isomerizate, (F IG. 2), there were two major differ- 4 ences. One was the relative size of the peak A, which contained the desired high melting 2,6-DMD isomer and the second characteristic difference was the emergence in the high temperature isomerizate of a VPC area-envelope A not present in the low equilibrium mixture. The relative decrease of the VPC peak A in the high temperature isomerizate could be predicted and rationalized on the basis of the temperature dependence of the equilibrium compositions of various DMD isomers (Equilibrium Compositions at O60C of C and C Bicyclic Saturated Hydrocarbons, Preprints ACS Div. Petrol. Chem., Chicago, August 30-Septemper 4, 1964, p. 112). Thus, from the computations based on the working model of non-bonded interactions the equilibrium concentration of the desired 2,6- DMD isomer (TSS) at 230C was calculated to be 13 to 14% compared to 23% at room temperature. Since an equivalent decrease was to be expected for the corresponding STS 2,7-DMD isomer also present under peak A the experimentally observed decrease of the peak agreed well with the calculated equilibrium distribution. The identity of the numerous compounds under the broad envelope of the VPC area A could not be determined at this time. Thus, collection of the com pounds under peak area A by the preparative scale chromatography and the subsequent analysis of the mixture by the capillary chromatography showed the presence of at least 40 different compounds (FIG. 3). The general chemical characteristic of these compounds was their refractive nature under standard dehydrogenation conditions. i.e., they were not converted to dimethylnaphthalenes.

The assumption that some of these unknown compounds were either gem.-disubstituted or bridgehead substituted dimethyldecalins was corraborated indirectly by dehydrogenation under severe conditions whereby land 2-methylnaphthalenes were present in the catalysate in admixture with the unchanged starting material (FIG. 4). Therefore, in addition to the dimethyldecalins with one or two quaternary carbons, other C-12 bicyclanes such as alkylbicyclononanes and alkylbicyclo-octanes are present in the mixture. In general, these bicyclanes are favored at higher temperatures and have been reported to be present in the crude petroleum fractions. Due to the complexity of the mixture of the "non-dehydrogenatables and difficulty in the separation of the individual compounds by the standard separation techniques, have not been precisely characterized.

The fact that the lower boiling non-dehydrogenatables present in the high temperature DMD isomerizate were still C-12 dicyclics were demonstrated by the conversion of the total high temperature isomerizate to the characteristic low temperature DMD equilibrium isomerizate to the characteristic low temperature DMD equilibrium isomerizate by the AlBr -HBr-complex at room temperature (FIG. 5).

The DMD equilibrium isomerizate thus obtained afforded on dehydrogenation the typical DMN equilibrium mixture (FIGS. 6 and 7).

In addition to the general catalyst screening by the pulse microreactor technique batch and recirculating reactor runs with certain selected catalysts were carried out to determine the isomeric composition of the high temperature equilibrium mixture as well as the optimal reaction conditions.

To determine the position of the thermodynamic equilibrium at an elevated reaction temperature two different charge stocks, 2,3-DMDs and 2,7-DMDs (vide supra) were isomerized independently over SK- the relatively early stage-of the reaction, e.g., 18 to 20% 1 of the final 22 to 25% of these compounds were present after ca. 4 hours. The DMN analysis of the dehydrogenates showed the total 2,6DMN content of 16% on the whole sample basis and 20 to 21% normalized for DMNs. The weight balances for the two DMD equilibrium isomerizates after 16 hours were 87% for the 2,3-DMD and 94% for the 2,7-DMD isomerizate's. The material loss occurred presumably by cracking to lighter hydrocarbons which were lost in the course of the reaction as well as attendant mechanical losses.

The same catalyst, SK-l was employed with mixed DMDs in the insomerization study in the gas phase-liquid phase recirculating reactor. The objective of this study was to determine the catalyst aging effects under continuous flow conditions and to observe, if possible, kinetic effects in the preferential formation of certain isomers.

The results with the recirculating reactor paralleled the findings with the liquid phase batch reactor. A total of 15 to 20 individual cycles with to overhead take-off per cycle were necessary to equilibrate mixed DMDs at LI-ISV of 12, i.e., cumulative reaction time of 10 hours at 250C. The non-dehydrogenatables appeared early, i.e., after two to three recycles. Again, 10 to 15% of the charge was lost as the low boiling cracking products. An attempt to, promote the reaction by the addition of a slow stream of hydrogen chloride to the ebullating DMD charge had no effect, i.e., noincrease in the isomerization rate was observed. Also, addition of organic halide promoters such as l,4-bischloromethyl cycloheXane, bis-1,2-chloroethoxyethane and bromomethyladamantane to the DMD charge resulted in little, if any, enhancement of the isomerization rate (Table III) Finally, to determine the effect of a noble metal and hydrogen pressure on the catalyst life in the isomerization of dime'thyldecalins, a 15 hour continuous flow reactor run was carried out with mixed DMDs at 235C, 200 psigH over a special, palladium loaded SK-l30 catalyst (Pd/RE-Y).

No significant decrease in the catalyst activity was observed after the above time period with cumulative 56 ml DMD-cyclohexane (1:1) feed per gram of the catalyst. Thus, the ratio of peak A to B, an index for the approach to equilibrium, was ca. 0.86 throughout the run (FIG. 10). A ratio of 0.89 was obtained after first and 0.92 after the second recycle (FIGS. 11 and 12).

TABLE I REACTION OF MIXED DIMETI-IYLDECALINS (M-DMD) IN A PULSE MICROREACTOR OVER MOLE SIEVE CATALYSTS Pulse PH2 P Catalyst Size Feed H flow Run No. (mg) Feed (ul) Cat. TC ml/min. Result 5000-1 SK-l l0 M-DMD 50 l 278 I00 B, I

(50) 20% in CH 5000-2 M-DMD B, I

20% in C H 500l-l SK-ZOO M-DMD f NR 20% in CH 500l-2 300 I00 B 20 5002-l Ni-l-IY 278 100 B, l

I (50) I00 50022 262 f C, I 4987-2 Ce-Y M-DMD 10 0.085 276 I00 A II II I! I! II A I 100 4987-4 M-DMD 50 p 0.43 B, I

20% in CH I: II II- 1! n B. 4987-8 0.43 275 I50 B, I

190 4998-1 H-Zeolon 0.45 278 100 C, NR I I0) I00 4998a n H I, M 3m H B. NR 4999-1 SK-l30 0.50 275 A, I

4999-2 I 265 C, I;

DMD concentrate 08332556 (MMD-27.07c. DMD-61.6%. Others-l 1.4%(DMD?) "A extensive 50%) cracking or hydmcracking to lighter hydrocarbons.

B substantial (-20-50%) cracking or hydrocracking to lighter hydrocarbons.

C moderate -520%-) cracking or hydrocracking to lighter hydrocarbons.

I isomerization of DMDs to equilibrium or near equilibrium l isomerization of DMDs to an atypical product distribution NR- no reaction CH- cyclohexane TABLE II ISOMERlZATlON OF 2.3- and 2,7-DIMETHYLDECAL1NS OVER SK-13O CATALYST AT 200C. LIQUID PHASE. BATCH REACTOR Cumulative VPC Anal. (wt.%) After Dehydrogenation Rx 2,3- Sample Time Other 2.6- 2.7- 1,6- 1.7 1.4-

No. (min.)" A" 2-MeN l-MeN Bi-Ph lEtN 2-EtN DMN DMN DMN 1.3- 1.5- 1.2-

DMN DMN DMN 2.3-DMD 225 19.6 4.6 1.1 2.7 25.5 29.4 13.7 3.4 5003-1" 5.7 1.4 3 31.8 36.6 17.1 4.1

5.5 1.0 0.4 3.9 16.3 16.1 21.8 22.2 12.8 645 22.3 5.0 1.2 3.8 29.5 27.3 8.3 2.6 6.4 1.6 4.9 37.9 35.2 10.7 3.3 6.0 0.9 tr. 5.4 20.2 19.2 24.0 16.0 6.6 5003-2 985 24.0 4.2 1.0 3.7 30.9 26.2 7.7 2.3 h 5.5 1.3 4.9 40.6 34.5 10.1 3.1 2,7-DMD" 5003-4" 225 18.3 7.9 1.9 1.2 36.6 26.6 5.8 1.7 i 9.6 2.3 1.5 44.8 32.6 7.1 2.1

8.9 2.1 0.1 2.0 23.2 23.0 25.0 11.0 3.8 5003-5 645 20.6 5.6 1.5 2.6 32.5 27.4 7.3 2.5 h 7.0 1.9 3.3 41.0 34.5 9.2 3.1 i 6.7 1.6 0.2 3.9 21.5 21.0 24.5 14.3 5.9 5003-6 985 21.8 5.4 1.4 2.9 31.8 27.0 7.5 2.2 h 6.9 1.8 3.7 40.6 34.5 9.6 2.9 i 5.8 1.0 tr. 4.7 22.1 21.4 25.0 14.5 5.3

SK-130. milled to 20 mesh size (air exposure 2 min.). mechanical stin'ing. slow N flow. Wt. Loss after 16.5 hrs. 13% for 2.3-DMD and 6% for 2.7'DMD.

2.3- and 2.7-DMN hydrogenated over Raney Ni. 220. 300C (6. 12 hrs.). VPC trace on a 30'. 3/16" DEGS column shows 4 peaks for 2,3-DMD's and 3 peaks for 2.7-DMDs. Obtained from Dr. .1. Hedge (code Ill-515671, .lH-S l5668-D3).

Temp. of the oil bath.

Time count only for the period at 200C. reaction carried out over the interval of several days.

"Compounds with retention time less than dimethylnaphthalenes. VPC trace shows 45 peaks. A small quantity of light C hydrocarbons also present. 'Dehydrogenation by the pulse microreactor technique (connected to the VPC column) over lithiated RDlSO catalyst.

"Direct measurement of the dehydrogenate from the pulse microreactor (DEGS column. 30') "Ditto normalized to DMN's 'DMNs only trapped in the capillary from g. analyzed by the Analytical Section on Bentone column.

TABLE III lSOMERlZATlON F DIMETHYLDECALINS OVER SK-130. XZ-36 AND AMBERLYST 15 CATALYSTS B/A Exp. No. Catalyst(gms.) DMD (gms.) Sample Time (hours) Temp.C Initiator (m1) Peak Ratio 515671 SK-130 2.3- (515671) 1 3.7 200 None 1.3 (25.0) (100.0) 2 5.0 1.1 3 7.1 1.0 9.5 0.98 6 12.7 0.94 7 12.8 0.93 546302 SK-130 2.3- (515671) 1 1.7 0.04 ml A 7.9 10.0) (40.0) 3 4.0 2.3 5 6.0 0.4 m1 A 1.4 7 7.0 1.1 10 1.1 546303 SK-130 DMD(s), mixed 1 1.7 154 0.4 ml B (10.0) RU-S 14966 2 3.2 149 (40.0) 3 4.2 153 1.5 4 6.2 1.4 5 6.5 150 1.4 6 7.5 0.8 m1 A 7 9.7 1.3 8 10.7 1.2 9 11.7 1.2 10 12.7 546304 SK-130 2,3- (512966) 1 2.5 140 None N.R.

(5.0 gms.) (20.0) 2 3.5 3 5.5 142 0.2 ml A 12 4 8.0 9.0 5 9.1 8.9 6 12.0 8.1 7 14.5 0.2 m1 C 8 16.0 2.0 ml B 5.7 9 19.0 5.5 10 20.5 5.2 546305A Amberlyst 15 2.3- (512966) 1 4.5 None N.R.

(5.0) (20.0) 2 7.0 3 8.0 0.8 ml B 4 1 1.7 12.7 200 0.8 ml B 5 17.7 0.3 m1 C 6 19.7 546306 SK-130 23 (512966) 1 1.0 A" 63 (5.0) (20.0) 2 3.0 5.6 3 3.4 546306A XZ-36 2.3- (512966) 1 1.2 200 None N.R.

TABLE Ill-continued ISOMERIZATION 0F DIMETHYLDECALINS OVER SK-l30, XZ-36 AND AMBERLYST 1s CATALYSTS Exp. No. Catalyst(gms.) DMD (gms) From relative peak heights (Sl567l only) "Ratio BIA in the starting material 2.05 Integrator faulty here A 1.4 Bis-(chloromethyl)cyclohexane B 1.2 Bis2 chloroethoxyethane C l-Bromo-3.S-dimethyladamantane Addition of 2.0 mls. in 8.0 mls. of A between the first and second hours.

The invention claimed is:

l. A process for conversion of a feed consisting es-- sentially of an alkyldecalin or an alkyltetralin or a nonequilibrium mixture thereof, said process comprising contacting said feed under, conversion conditions with an aluminosilicate zeolite containing polyvalent metal cations in exchange positions, said contacting being at a temperature in the 'range of 100C to 350C, at a liquid hourly space velocity in the range of 0.25 to 10, and at a pressure in the range of to 1500 psig.

2. Process of claim 1 wherein said feed contains at least one dimethyldecalin isomer, or a mixture of dimethyldecalins and dimethyltetralins.

3. Process according to claim 2 wherein said feed consists essentially of two or more dimethyldecalins and is relatively lean with respect to 2,6-DMT and rich with respect to one or more members of the 2,7-DMT family and wherein the resulting conversion product is enriched with respect to 2,6-DMT.

4. Process of claim 1 wherein gaseous hydrogen is also present and said contacting is with said zeolite and a hydrogenation-dehydrogenation catalyst comprises at least one member selected from platinum, ruthenium, rhenium, palladium, and chemical compounds thereof.

5. Process of claim 1 wherein said zeolite is in the range of ID to 100% crystalline by X-ray analysis.

6. Process of claim 5 wherein said crystalline portion of said zeolite has an alumino-silicate framework of the faujasite cage structure.

Sample Time (hours) Temp.C initiator (ml) 7. Process of claim 1 wherein said framework has an Al/Si ratio in the range of 0.35 to 0.65.

8. Process of claim 1 wherein at least 20% of the electronegativity associated with said alumino-silicate is satisfied by cations of nickel, lanthanum or a rare earth or oxides or hydroxides thereof.

9. Process of claim 8 wherein said zeolite contains less than one alkali metal cation for every four aluminum atoms in said alumino-silicate.

10. Process of claim 4 wherein said hydrogenationdehydrogenation catalyst comprises 0.05 to 25 weight percent of platinum, palladium or a chemical compound of platinum or palladium and wherein said zeolite contains less than one alkali metal cation for every four aluminum atoms in said framework and at least 40% of the electronegativity associated with said framework is satisfied by at least one member selected from cations of at least one member selected from nickel, lanthanum, the rare earths and oxides and hydroxides thereof.

11. Process of claim 2 wherein the conversion temperature is in the range of to 250C.

12. Process of claim 1 wherein said feed contains at least one dimethyldecalin isomer or a mixture of a number of dimethyldecalin positional and stereo-isomers, or a mixture of said dimethyldecalins and a mixture of dimethyltetralins. 

1. A PROCESS FOR CONVERSION OF A FEED CONSISTING ESSENTIALLY OF AN ALKYLDECALIN OR AN ALKYLTERTRALIN OR A NON-EQUILLIBRIUM MIXTURE THEREOF, SAID PROCESS COMPRISING CONTACTING SAID FEED UNDER CONVERSION CONDITIONS WITH AN ALIMINOSILICATE ZEOLIE CONTAINING POLYVALENT METAL CATIONS IN EXCHANGE POSITIONS, SAID CONTACTING BEING AT A TEMPERATURE IN THE RANGE OF 100*C TO 350*C, AT A LIQUID HOURLY SPACE VELOCITY IN THE RANGE OF 0.25 TO 10, AND AT A PRESSURE IN THE RANGE OF 15 TO 1500 PSIG.
 2. Process of claim 1 wherein said feed contains at least one dimethyldecalin isomer, or a mixture of dimethyldecalins and dimethyltetralins.
 3. Process according to claim 2 wherein said feed consists essentially of two or more dimethyldecalins and is relatively lean with respect to 2,6-DMT and rich with respect to one or more members of the 2,7-DMT family and wherein the resulting conversion product is enriched with respect to 2,6-DMT.
 4. Process of claim 1 wherein gaseous hydrogen is also present and said contacting is with said zeolite and a hydrogenation-dehydrogenation catalyst comprises at least one member selected from platinum, ruthenium, rhenium, palladium, and chemical compoundS thereof.
 5. Process of claim 1 wherein said zeolite is in the range of 10 to 100% crystalline by X-ray analysis.
 6. Process of claim 5 wherein said crystalline portion of said zeolite has an alumino-silicate framework of the faujasite cage structure.
 7. Process of claim 1 wherein said framework has an Al/Si ratio in the range of 0.35 to 0.65.
 8. Process of claim 1 wherein at least 20% of the electronegativity associated with said alumino-silicate is satisfied by cations of nickel, lanthanum or a rare earth or oxides or hydroxides thereof.
 9. Process of claim 8 wherein said zeolite contains less than one alkali metal cation for every four aluminum atoms in said alumino-silicate.
 10. Process of claim 4 wherein said hydrogenation-dehydrogenation catalyst comprises 0.05 to 25 weight percent of platinum, palladium or a chemical compound of platinum or palladium and wherein said zeolite contains less than one alkali metal cation for every four aluminum atoms in said framework and at least 40% of the electronegativity associated with said framework is satisfied by at least one member selected from cations of at least one member selected from nickel, lanthanum, the rare earths and oxides and hydroxides thereof.
 11. Process of claim 2 wherein the conversion temperature is in the range of 150* to 250*C.
 12. Process of claim 1 wherein said feed contains at least one dimethyldecalin isomer or a mixture of a number of dimethyldecalin positional and stereo-isomers, or a mixture of said dimethyldecalins and a mixture of dimethyltetralins. 